Question 282360
This problem appears every couple weeks.
x-x/3-1/3(x-x/3)-1/3(x-x/3-1/3(x-x/3))=8
x=27

first guy ate 1/3*27=9 leaving 18
next guy ate 18/3=6 leaving 12
3rd guy at 12/3=4 leaving 8

A simpler way to calculate by working backwards
2/3x=8
x=12
2/3x=12
x=18
2/3x=18
x=27